[teamai] Push 87 resource(s) from XingfenD
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# Operators Guide
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samber/ro provides 150+ operators organized by category. All operators are generic functions that take and return `Observable[T]`, designed for chaining via `Pipe`.
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## Pipeline Construction
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```go
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// Typed pipes (Pipe1 through Pipe25) — compile-time type safety
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result := ro.Pipe2(source, op1, op2)
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result := ro.Pipe3(source, op1, op2, op3)
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// Untyped pipe — uses any, loses type checking
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result := ro.Pipe(source, op1, op2, op3)
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// Reusable operator composition (curried)
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transform := ro.PipeOp2(op1, op2) // returns func(Observable[A]) Observable[C]
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result := transform(source)
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// Synchronous collection
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values, err := ro.Collect(observable)
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```
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## Creation Operators
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Create observables from various sources. Typically the first argument to `Pipe`.
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| Operator | Signature | Purpose |
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| --- | --- | --- |
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| `Just` | `Just[T](values ...T) Observable[T]` | Emit specific values then complete |
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| `Of` | `Of[T](values ...T) Observable[T]` | Alias for Just |
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| `FromSlice` | `FromSlice[T](items []T) Observable[T]` | Create from existing slice |
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| `FromChannel` | `FromChannel[T](ch <-chan T) Observable[T]` | Wrap Go channel as observable |
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| `Range` | `Range(start, end int) Observable[int]` | Emit integer sequence |
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| `RangeWithStep` | `RangeWithStep(start, end, step int) Observable[int]` | Integer sequence with custom step |
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| `RangeWithInterval` | `RangeWithInterval(start, end int, d time.Duration) Observable[int]` | Integers with delay between each |
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| `RangeWithStepAndInterval` | `RangeWithStepAndInterval(start, end, step int, d time.Duration) Observable[int]` | Step + interval combined |
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| `Interval` | `Interval(d time.Duration) Observable[int64]` | Emit sequential integers at intervals (infinite) |
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| `IntervalWithInitial` | `IntervalWithInitial(initial, d time.Duration) Observable[int64]` | Interval with initial delay |
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| `Timer` | `Timer(d time.Duration) Observable[int64]` | Single emission after delay |
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| `Repeat` | `Repeat[T](item T, count int64) Observable[T]` | Repeat item N times |
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| `RepeatWithInterval` | `RepeatWithInterval[T](item T, count int64, d time.Duration) Observable[T]` | Repeat with delay |
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| `Defer` | `Defer[T](factory func() Observable[T]) Observable[T]` | Lazily create observable on subscription |
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| `Future` | `Future[T](factory func() (T, error)) Observable[T]` | Single async value from function |
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| `Start` | `Start(cb func() (any, error)) Observable[any]` | Execute callback and emit result |
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| `Empty` | `Empty[T]() Observable[T]` | Complete immediately, no values |
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| `Never` | `Never[T]() Observable[T]` | Never emit or complete |
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| `Throw` | `Throw[T](err error) Observable[T]` | Immediately error |
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```go
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// Custom observable with direct control
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obs := ro.NewObservable[int](func(ctx context.Context, observer ro.Observer[int]) error {
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observer.Next(1)
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observer.Next(2)
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observer.Complete()
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return nil
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})
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```
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## Transformation Operators
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Transform each value in the stream.
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| Operator | Purpose |
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| --- | --- |
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| `Map[T, R](fn func(T) R)` | Transform each value T -> R |
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| `MapI[T, R](fn func(T, int64) R)` | Map with index |
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| `MapErr[T, R](fn func(T) (R, error))` | Map that can fail — error propagates |
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| `MapWithContext[T, R](fn func(ctx, T) (ctx, R))` | Map with context access |
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| `MapTo[T, R](output R)` | Replace all values with a constant |
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| `FlatMap[T, R](fn func(T) Observable[R])` | Map each value to observable, flatten results |
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| `MergeMap[T, R](fn func(T) Observable[R])` | Alias for FlatMap |
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| `Scan[T, R](fn func(R, T) R, seed R)` | Running accumulation, emit each intermediate |
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| `Reduce[T, R](fn func(R, T) R, seed R)` | Accumulate, emit only final result |
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| `GroupBy[T, K](fn func(T) K)` | Partition into grouped observables by key |
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| `Cast[T, U]()` | Type cast values |
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| `Flatten[T]()` | Flatten `Observable[[]T]` to `Observable[T]` |
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| `Materialize[T]()` | Wrap values in `Notification[T]` (next/error/complete) |
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| `Dematerialize[T]()` | Unwrap `Notification[T]` back to values |
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| `Timestamp[T]()` | Emit `TimestampValue[T]` with emission time |
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| `TimeInterval[T]()` | Emit `IntervalValue[T]` with time since last emission |
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```go
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// FlatMap: for each user ID, fetch their orders (returns observable)
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orders := ro.Pipe2(
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userIDs,
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ro.FlatMap(func(id int) ro.Observable[Order] {
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return fetchOrders(id)
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}),
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ro.Filter(func(o Order) bool { return o.Status == "paid" }),
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)
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// Scan: running sum
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ro.Pipe1(
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ro.Just(1, 2, 3, 4, 5),
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ro.Scan(func(acc, x int) int { return acc + x }, 0),
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)
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// Emits: 1, 3, 6, 10, 15
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```
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## Filtering Operators
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Selectively emit values from the stream.
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| Operator | Purpose |
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| --- | --- |
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| `Filter[T](fn func(T) bool)` | Emit only values matching predicate |
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| `FilterI[T](fn func(T, int64) bool)` | Filter with index |
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| `FilterWithContext[T](fn func(ctx, T) (ctx, bool))` | Filter with context access |
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| `Distinct[T comparable]()` | Emit only unique values |
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| `DistinctBy[T, K](fn func(T) K)` | Unique by key function |
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| `Take[T](n int64)` | Emit first N values then complete |
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| `TakeLast[T](n int)` | Emit last N values |
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| `TakeWhile[T](fn func(T) bool)` | Emit while predicate true, then complete |
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| `TakeUntil[T, S](signal Observable[S])` | Emit until signal observable emits |
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| `Skip[T](n int64)` | Skip first N values |
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| `SkipLast[T](n int)` | Skip last N values |
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| `SkipWhile[T](fn func(T) bool)` | Skip while predicate true |
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| `SkipUntil[T, S](signal Observable[S])` | Skip until signal emits |
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| `Head[T]()` | First item only |
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| `Tail[T]()` | All items except first |
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| `ElementAt[T](n int)` | Item at specific index |
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| `ElementAtOrDefault[T](n int64, fallback T)` | Item at index or default |
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| `Find[T](fn func(T) bool)` | First value matching predicate |
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| `First[T](fn func(T) bool)` | First matching value (alias-like) |
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| `Last[T](fn func(T) bool)` | Last matching value |
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| `Contains[T](fn func(T) bool)` | Emit bool: whether any value matches |
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All filtering operators have `I` (indexed), `WithContext`, and `IWithContext` variants.
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## Combining Operators
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Merge multiple observables into one.
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| Operator | Purpose |
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| --- | --- |
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| `Merge[T](sources ...Observable[T])` | Interleave emissions from all sources |
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| `MergeWith[T](obs ...Observable[T])` | Chainable merge |
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| `MergeAll[T]()` | Flatten `Observable[Observable[T]]` by merging |
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| `Concat[T](obs ...Observable[T])` | Sequential: complete first, then start second |
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| `ConcatWith[T](obs ...Observable[T])` | Chainable concat |
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| `ConcatAll[T]()` | Flatten by concatenating sequentially |
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| `Zip2[A, B](a, b)` | Pair values from 2 sources into `lo.Tuple2` |
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| `Zip3` ... `Zip6` | Zip 3-6 sources into corresponding `lo.Tuple` |
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| `ZipWith[A, B](obsB)` | Chainable zip |
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| `CombineLatest2[A, B](a, b)` | Emit combined latest when either source emits |
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| `CombineLatest3` ... `CombineLatest5` | Combine 3-5 sources |
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| `CombineLatestWith[A, B](obsB)` | Chainable combine-latest |
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| `Race[T](sources ...Observable[T])` | Emit from whichever source emits first |
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| `Amb[T](sources ...)` | Alias for Race |
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| `StartWith[T](prefixes ...T)` | Prepend values before source emissions |
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| `EndWith[T](suffixes ...T)` | Append values after source completes |
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```go
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// Zip: pair user with their settings
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ro.Zip2(userStream, settingsStream)
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// Emits: lo.Tuple2[User, Settings]
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// CombineLatest: re-emit whenever either changes
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ro.CombineLatest2(priceStream, quantityStream)
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// Emits latest (price, quantity) pair each time either updates
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```
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## Math and Aggregation
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| Operator | Purpose |
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| --- | --- |
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| `Count[T]()` | Count of emitted values |
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| `Sum[T Numeric]()` | Sum of all values |
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| `Average[T Numeric]()` | Average as float64 |
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| `Max[T Numeric]()` | Maximum value |
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| `Min[T Numeric]()` | Minimum value |
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| `Abs()` | Absolute value (float64) |
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| `Ceil()` / `Floor()` / `Round()` / `Trunc()` | Rounding (float64) |
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| `CeilWithPrecision(n)` / `FloorWithPrecision(n)` | Rounding with decimal places |
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| `Clamp[T](lower, upper)` | Constrain values to range |
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## Error Handling
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| Operator | Purpose |
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| --- | --- |
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| `Catch[T](fn func(error) Observable[T])` | Catch error, switch to recovery observable |
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| `OnErrorReturn[T](value T)` | Replace error with fallback value |
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| `OnErrorResumeNextWith[T](obs ...Observable[T])` | Continue with fallback observables on error |
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| `Retry[T]()` | Retry indefinitely on error |
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| `RetryWithConfig[T](cfg RetryConfig)` | Retry with max attempts, delay, backoff |
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| `ThrowIfEmpty[T](fn func() error)` | Error if stream completes empty |
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```go
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// RetryConfig for exponential backoff
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ro.RetryWithConfig[Response](ro.RetryConfig{
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Max: 3,
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Delay: time.Second,
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BackoffMultiplier: 2.0,
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MaxDelay: 10 * time.Second,
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})
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```
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## Timing and Buffering
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| Operator | Purpose |
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| --- | --- |
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| `Delay[T](d time.Duration)` | Delay entire stream |
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| `DelayEach[T](d time.Duration)` | Delay between each emission |
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| `Timeout[T](d time.Duration)` | Error if no emission within duration |
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| `ThrottleTime[T](d time.Duration)` | Ignore values within duration of last |
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| `ThrottleWhen[T, t](tick Observable[t])` | Throttle by signal |
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| `SampleTime[T](d time.Duration)` | Emit latest value at intervals |
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| `SampleWhen[T, t](tick Observable[t])` | Sample by signal |
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| `BufferWithCount[T](n int)` | Collect N items, emit as `[]T` |
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| `BufferWithTime[T](d time.Duration)` | Collect within time window |
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| `BufferWithTimeOrCount[T](n, d)` | Buffer with either condition |
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| `BufferWhen[T, B](boundary Observable[B])` | Buffer until signal |
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| `WindowWhen[T, B](boundary Observable[B])` | Window as nested observables |
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| `Pairwise[T]()` | Emit consecutive pairs |
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## Side Effects (Tap / Do)
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Execute code without changing the stream. `Do` is an alias for `Tap`.
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| Operator | Purpose |
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| ------------------------------------- | --------------------------- |
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| `Tap[T](onNext, onError, onComplete)` | Side effect on all events |
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| `TapOnNext[T](fn func(T))` | Side effect on values |
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| `TapOnError[T](fn func(error))` | Side effect on errors |
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| `TapOnComplete[T](fn func())` | Side effect on completion |
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| `TapOnSubscribe[T](fn func())` | Side effect on subscription |
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| `TapOnFinalize[T](fn func())` | Side effect on teardown |
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All have `WithContext` variants. `Do`, `DoOnNext`, `DoOnError`, `DoOnComplete`, `DoOnSubscribe`, `DoOnFinalize` are aliases.
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## Connectable and Sharing
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| Operator | Purpose |
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| --- | --- |
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| `Share[T]()` | Cold -> hot with reference counting |
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| `ShareWithConfig[T](cfg ShareConfig[T])` | Share with reset options |
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| `ShareReplay[T](bufferSize int)` | Share + replay last N values to late subscribers |
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| `ShareReplayWithConfig[T](n, cfg)` | ShareReplay with reset options |
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| `Serialize[T]()` | Queue emissions to ensure serial delivery |
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```go
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// ShareConfig controls lifecycle reset
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ro.ShareConfig[T]{
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ResetOnComplete: true, // re-subscribe on complete
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ResetOnError: true, // re-subscribe on error
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ResetOnReferenceCount: true, // re-subscribe when count drops to 0
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}
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```
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## Context Operators
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| Operator | Purpose |
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| ---------------------------------------- | ------------------------------- |
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| `ContextReset[T](ctx context.Context)` | Replace pipeline context |
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| `ContextWithValue[T](key, value any)` | Add value to context |
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| `ContextWithTimeout[T](d time.Duration)` | Add timeout |
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| `ContextWithDeadline[T](t time.Time)` | Add deadline |
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| `ContextMap[T](fn func(ctx) ctx)` | Transform context |
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| `ThrowOnContextCancel[T]()` | Error when context is cancelled |
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## Conditional Operators
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| Operator | Purpose |
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| --- | --- |
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| `All[T](fn func(T) bool)` | Emit bool: whether all values match |
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| `DefaultIfEmpty[T](value T)` | Emit default if source completes empty |
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| `ThrowIfEmpty[T](fn func() error)` | Error if empty |
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| `Iif[T](pred func() bool, a, b Observable[T])` | Choose between two observables |
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| `While[T](cond func() bool)` | Repeat while condition true |
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| `DoWhile[T](cond func() bool)` | Execute at least once, repeat while true |
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| `SequenceEqual[T](obsB Observable[T])` | Emit bool: whether two streams match |
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## Terminal Operators
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| Operator | Purpose |
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| --- | --- |
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| `Collect[T](obs Observable[T]) ([]T, error)` | Block, return all values as slice |
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| `CollectWithContext[T](ctx, obs) ([]T, ctx, error)` | Collect with context |
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| `ToSlice[T]()` | Operator: emit `[]T` on complete |
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| `ToChannel[T](size int)` | Convert to `<-chan Notification[T]` |
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| `ToMap[T, K, V](fn func(T) (K, V))` | Collect into map |
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## Observer and Subscription
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```go
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// Full observer (recommended)
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observer := ro.NewObserver[T](onNext, onError, onComplete)
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// Context-aware observer
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observer := ro.NewObserverWithContext[T](onNext, onError, onComplete)
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// Convenience shortcuts
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observer := ro.OnNext[T](func(v T) { ... })
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observer := ro.PrintObserver[T]() // debug: prints all events
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observer := ro.NoopObserver[T]() // discard all events
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// Subscription lifecycle
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sub := observable.Subscribe(observer)
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sub.Wait() // block until complete or error
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sub.Unsubscribe() // cancel and cleanup
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sub.IsActive() // check if still running
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sub.GetError() // get terminal error
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```
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## Scheduling
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| Operator | Purpose |
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| -------------------------------- | ---------------------------------------- |
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| `SubscribeOn[T](bufferSize int)` | Run subscription on async scheduler |
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| `ObserveOn[T](bufferSize int)` | Deliver notifications on async scheduler |
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## Concurrency Modes
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```go
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// Safe (default): synchronized emissions
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ro.NewObservable[T](fn)
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ro.NewSafeObservable[T](fn)
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// Unsafe: no synchronization, caller must guarantee single-goroutine access
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ro.NewUnsafeObservable[T](fn)
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// Eventually safe: allows brief unsynchronized period, then synchronizes
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ro.NewEventuallySafeObservable[T](fn)
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```
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Block a user